An installation of the above type is described in the specification of French patent application No. 93 04273 filed on 9 Apr. 1993 in the name of Valeo Thermique Habitacle. In that installation, the heating apparatus also includes a blower for delivering heated air into the cabin via air outlet ports which are separate from the air outlet ports of the ventilating and air conditioning apparatus. In the installation disclosed in the above mentioned French patent application, the heating apparatus and the ventilating and air conditioning apparatus may be disposed in aligned relationship in a direction which is substantially horizontal with respect to longitudinal axis of the vehicle, the heating apparatus being arranged in front of the ventilating and air conditioning apparatus. In a modification, the heating apparatus and the ventilating and air conditioning apparatus may be arranged side by side. In either one of these arrangements, both apparatuses are disclosed in a central region of the fascia panel.
Such installations are most particularly suitable to vehicles of the "monobody" or "monocorps" type, in which the windshield is steeply inclined and forms, in effect, an upward and rearward extension of the motor hood, while the fascia panel is of a form in which it is very much elongated in a longitudinal direction into the cabin itself. Advantage can then be taken of this elongation of the fascia panel, so as to arrange centrally in it both the heating apparatus and the ventilating and air conditioning apparatus.
In such vehicles it has been found that under certain circumstances two hot air zones can form in the cabin, and that these zones are detrimental to satisfactory operation of the ventilating and air conditioning apparatus. One of these zones is above the panel and behind the windshield, and is created by solar radiation through the windshield. The air in this zone is heated to a greater extent the larger the windshield surface, and the more the windshield is inclined to the horizontal.
The other hot air zone lies in the lower part of the cabin, below the fascia panel and behind the motor compartment. This hot air zone is due essentially to heating of the air by heat radiated by the motor, which is arranged in a motor compartment lying immediately in front of the cabin of the vehicle.
These hot air zones are thus due mainly to the particular structure of the monobody type of vehicle, and the fascia panel acts as a screen between these two zones so that the air in each zone tends to become stagnant. Thus the existence of these two hot air zones is detrimental to good mixing of the air in the cabin of the vehicle.